While there is widespread consensus that the optimal diet to reduce cardiovascular risk should be low in saturated fat, the type of macronutrient that should replace saturated fat (carbohydrate, protein or unsaturated fat) is a major, unresolved research question with substantial public health implications. The proposed study will evaluate these 3 dietary approaches by studying their effects on established coronary risk factors and a selected group of emerging risk factors. The study design is a randomized, three period cross-over feeding study that will compare the effects on blood pressure and plasma lipids of a carbohydrate-rich diet (the DASH diet) to two other diets, one rich in protein and another rich in unsaturated (UNSAT) fat, predominantly monounsaturated fat. The DASH diet has been shown to reduce blood pressure and LDL-cholesterol substantially, and is currently recommended by policy makers. During a 1 week run- in, all participants will be fed samples of the 3 study diets (DASH, PROTEIN and UNSAT). Using a three period cross-over design, participants will then be randomly assigned to the DASH, PROTEIN OR UNSAT diet. Each feeding period will last 6 weeks; a washout period of at least 2 weeks will separate each feeding period. Throughout feeding (run-in and the 3 intervention periods), participants will be fed sufficient calories to maintain their weight. Trial participants (n=200, approximately 50 percent female, approximately 50 percent African-American) will be 20 years of age or older, with systolic blood pressure of 120-159 mmHg and diastolic blood pressure of 80-95 mmHg. Primary outcomes variables will be blood pressure and the established plasma lipid risk factors (LDL-C, HDL-C and triglycerides). Secondary outcomes will include apolipoproteins VLDL-apoB and VLDL-apoCIII, which should be superior to triglycerides as predictors of cardiovascular events, as well as total apolipoprotein B, non-HDL cholesterol, and lipoprotein(a). In this fashion, the trial should advance our fundamental knowledge of the effects of diet on both traditional and emerging risk factors, and in the process, inform policy makers and health care providers on the relative benefits of carbohydrate, protein and unsaturated fat, predominantly monounsaturated fat, as means to reduce cardiovascular risk.